rebuilt 4.0 I6 weird noise , vibrations

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06-06-2012, 12:59 AM

#16

HAPPJAMES

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Location: Corona CA

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Year: 1987

Model: Cherokee

Engine: 4.0 LTR

little update so i inspected the firing order, turns out i had the number 4 and six spark plug wires mixed up thankfully after i fixed that it started up and was smooth no rough idle no engine vibrating, i still need to have the cat changed but i gota buddy who has a muffler shop so im sure i can get a good price just gotta pass smog in august. thanks for the help ya'll very much appreicated..

Also i got one more questionn the timing,,,,,i know its controlled by the PCM, but i was just curious as to the degree its suppose to fire before Top-Dead-Center Mines firing at 12 degrees before TDC at an idle....i've heard 8 degrees somewere but i cant remember maybe another car but anyone got any input on that?

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06-06-2012, 06:34 AM

#17

cruiser54

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Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Quote:

Originally Posted by Radi

It's OK. The air in my shop has Lucas added to it.

Seriously, I never bought into the "this filter is crap, that oil turns back into coal tar" stuff, figuring any major brand was probably good enough.... until I screwed a Fram on and got the start up knock. Took it off and it went away.

Yep. I figure there would be alot more good used 4.0s still running around if it weren't for oil filter makers who were happy to sell inferior products. Might not be a big deal in all other applications, but our Jeeps sure don't like them.